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Zorluk: ZorInitial Stabilization and Triage

A 25-year-old man is brought to the emergency department by paramedics following a witnessed generalized tonic-clonic seizure that lasted approximately 3 minutes. His roommate reports finding an empty prescription bottle of amitriptyline, which had been refilled the previous day, next to the patient. The patient has a history of major depressive disorder. Upon arrival, he is postictal, lethargic, and mumbling incomprehensibly, but he localizes to pain and his airway is currently patent. His skin is flushed, warm, and dry. Pupils are 6 mm bilaterally and sluggishly reactive to light. Mucous membranes are markedly dry. Vital signs show a temperature of 38.2°C (100.8°F), blood pressure of 82/45 mmHg, heart rate of 138/min, respiratory rate of 18/min, and oxygen saturation of 97% on room air. An electrocardiogram reveals sinus tachycardia with a QRS duration of 165 msec and a prominent terminal R wave measuring 4 mm in lead aVR. Which of the following is the most urgent initial step in the management of this patient?

  1. Administration of intravenous sodium bicarbonateCevap
  2. B
    Computed tomography scan of the head without contrast
  3. C
    Administration of intravenous physostigmine
  4. D
    Deferral of treatment pending comprehensive urine toxicology results
  5. E
    Immediate transfer to the inpatient psychiatric unit

Cevap

Administration of intravenous sodium bicarbonate is the most urgent step to treat the sodium channel blockade causing QRS prolongation and hypotension.
The patient's presentation of seizures, anticholinergic signs (flushed/dry skin, mydriasis, tachycardia, hyperthermia), hypotension, and a widened QRS complex is highly indicative of severe tricyclic antidepressant (TCA) toxicity. The amitriptyline overdose has caused blockade of the fast cardiac sodium channels, leading to the prominent QRS prolongation (165 msec) and the terminal R wave in lead aVR. A QRS duration greater than 100 msec is highly predictive of seizures, and a duration greater than 160 msec is highly predictive of lethal ventricular arrhythmias. The immediate, life-saving stabilization step is the administration of intravenous sodium bicarbonate. This acts by providing a high sodium load to overcome the competitive blockade and by alkalinizing the serum, which favors the non-ionized form of the drug, decreasing its binding to the sodium channels.

Adım Adım Çözüm

1
Identify the toxidrome and the patient's critical vulnerabilities based on the clinical presentation.
The patient has anticholinergic symptoms (dry skin, mydriasis, tachycardia, hyperthermia), hypotension, and a QRS duration of 165 msec, consistent with severe TCA overdose.
Recognizing TCA toxicity dictates the immediate resuscitation priorities.
2
Evaluate the immediate life threats.
The QRS prolongation (greater than 100 msec) and severe hypotension indicate profound cardiac toxicity with an imminent risk for ventricular arrhythmias.
Cardiac toxicity is the primary cause of mortality in TCA overdose.
3
Select the most appropriate initial stabilization intervention.
Intravenous sodium bicarbonate is selected.
It increases the serum sodium gradient across the myocardial cell membrane and alkalinizes the blood, which decreases the binding of the TCA to the fast sodium channels, thereby narrowing the QRS and improving blood pressure.

Anahtar Kavram

In severe tricyclic antidepressant (TCA) overdose presenting with QRS prolongation (>100 msec) or hypotension, intravenous sodium bicarbonate is the immediate and most critical stabilization step to prevent lethal arrhythmias.
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Initial Stabilization and Triage

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